JP2005179794A - Method for producing carbon fiber - Google Patents
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- JP2005179794A JP2005179794A JP2003418594A JP2003418594A JP2005179794A JP 2005179794 A JP2005179794 A JP 2005179794A JP 2003418594 A JP2003418594 A JP 2003418594A JP 2003418594 A JP2003418594 A JP 2003418594A JP 2005179794 A JP2005179794 A JP 2005179794A
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- 229920000049 Carbon (fiber) Polymers 0.000 title claims abstract description 70
- 239000004917 carbon fiber Substances 0.000 title claims abstract description 70
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 13
- 239000000835 fiber Substances 0.000 claims abstract description 277
- 238000003763 carbonization Methods 0.000 claims abstract description 112
- 238000000034 method Methods 0.000 claims abstract description 96
- 238000011282 treatment Methods 0.000 claims abstract description 90
- 229920002239 polyacrylonitrile Polymers 0.000 claims abstract description 21
- 230000005484 gravity Effects 0.000 claims description 85
- 238000005259 measurement Methods 0.000 claims description 24
- 238000011221 initial treatment Methods 0.000 claims description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- 230000007423 decrease Effects 0.000 claims description 13
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- 230000000704 physical effect Effects 0.000 abstract description 8
- 238000010000 carbonizing Methods 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 14
- 238000004513 sizing Methods 0.000 description 12
- 230000007704 transition Effects 0.000 description 11
- 238000004381 surface treatment Methods 0.000 description 10
- 238000012545 processing Methods 0.000 description 8
- 239000002243 precursor Substances 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 229920006240 drawn fiber Polymers 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000009987 spinning Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 2
- BAPJBEWLBFYGME-UHFFFAOYSA-N Methyl acrylate Chemical compound COC(=O)C=C BAPJBEWLBFYGME-UHFFFAOYSA-N 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000000921 elemental analysis Methods 0.000 description 2
- 238000001891 gel spinning Methods 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 238000002166 wet spinning Methods 0.000 description 2
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- 238000007088 Archimedes method Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000012681 fiber drawing Methods 0.000 description 1
- 238000007380 fibre production Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 230000007847 structural defect Effects 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明は高強度、高配向度、且つ高弾性率の炭素繊維の製造方法に関する。 The present invention relates to a method for producing carbon fiber having high strength, high degree of orientation, and high elastic modulus.
従来、ポリアクリロニトリル(ＰＡＮ)系繊維を原料として高性能の炭素繊維が製造されることは知られており、航空機を始めスポーツ用品まで広い範囲で使用されている。 Conventionally, it has been known that high-performance carbon fibers are produced from polyacrylonitrile (PAN) fibers as raw materials, and they are used in a wide range of aircraft and sporting goods.
とりわけ、高強度・高弾性率の炭素繊維は宇宙航空用途に使用されており、これらは更なる高性能化が求められている。 In particular, high-strength and high-modulus carbon fibers are used in aerospace applications, and these are required to have higher performance.
ＰＡＮ系前駆体繊維を用いて炭素繊維を製造する方法としては、前駆体繊維を２００〜３００℃の酸化性雰囲気下で延伸又は収縮を行いながら酸化処理(耐炎化処理)を行った後、３００〜１０００℃以上の不活性ガス雰囲気中で炭素化を行う方法が知られている。 As a method for producing a carbon fiber using a PAN-based precursor fiber, the precursor fiber is subjected to an oxidation treatment (flame resistance treatment) while being stretched or contracted in an oxidizing atmosphere at 200 to 300 ° C., and then 300 A method of carbonizing in an inert gas atmosphere at ˜1000 ° C. or higher is known.
とりわけ３００〜９００℃付近での炭素化工程の繊維処理方法は、炭素繊維の強度発現に大きく影響を及ぼし、これまでに多くの検討が行われてきた。 In particular, the fiber treatment method in the carbonization step at around 300 to 900 ° C. greatly affects the strength expression of the carbon fiber, and many studies have been conducted so far.
特許文献１では、耐炎化繊維を３００〜８００℃において、不活性雰囲気中２５％までの範囲で伸長を加えながら炭素化し、耐炎化繊維の原長に対し負とならないように処理することによって、高強度の炭素繊維を得ることが開示されている。 In Patent Document 1, the flame-resistant fiber is carbonized at 300 to 800 ° C. while being stretched in an inert atmosphere in a range of up to 25%, and processed so as not to be negative with respect to the original length of the flame-resistant fiber. It is disclosed to obtain high strength carbon fibers.
また、特許文献２、特許文献３では、５００℃付近での繊維長さの急激な変化をコントロールするため、３００〜５００℃、５００〜８００℃と、工程を２つに分けることで緻密な高強度炭素繊維が得られることが開示されている。 Moreover, in patent document 2 and patent document 3, in order to control the rapid change of the fiber length in the vicinity of 500 ° C., 300 to 500 ° C. and 500 to 800 ° C. are divided into two steps, so that the dense high It is disclosed that strong carbon fibers can be obtained.
さらに、特許文献４では、耐炎化繊維を不活性雰囲気中、比重が１．４５に達するまでの昇温速度を５０〜３００℃/分、さらに比重が１．６０〜１．７５に達するまでの昇温速度を１００〜８００℃／分とする２段炭素化を行うことにより、ボイドの少ない炭素繊維が得られることが開示されている。
Furthermore, in
特許文献５でも特許文献４と同様に、３００〜８００℃において昇温勾配をコントロールする事により緻密な炭素繊維が得られることが開示されている。
Similarly to
しかしながら、緻密、高配向度、高強度且つ高弾性率を有する炭素繊維を得るためには、最適な繊維物性での緊縮を行う事が必要であり、これらの方法に記載されている温度範囲や、昇温勾配だけでは繊維の緻密さをコントロールする事は難しく、またパラメーターとして比重だけでは、緻密、高配向度、高強度且つ高弾性率を有する炭素繊維を得ることは困難で、従来より緻密、高配向度、高強度且つ高弾性率の炭素繊維を得るための方法が求められている。 However, in order to obtain a carbon fiber having a denseness, a high degree of orientation, a high strength and a high elastic modulus, it is necessary to perform stringency with optimum fiber properties, and the temperature range described in these methods and However, it is difficult to control the density of the fiber only by the temperature gradient, and it is difficult to obtain a carbon fiber having a high density, high orientation degree, high strength and high elastic modulus only by specific gravity as a parameter. There is a need for a method for obtaining carbon fibers having a high degree of orientation, high strength, and high elastic modulus.
さらに、従来の炭素化工程においては、毛羽が多くなったり、ストランド形態についてストランドの引揃え性が乱れ、その結果として品位が悪くなったりするなどの問題がある。
本発明者等は、長年にわたり鋭意検討を重ねた結果、ＰＡＮ系耐炎化繊維を炭素化する炭素化工程を、第一炭素化工程と第二炭素化工程とで構成させた。 As a result of intensive studies over many years, the present inventors have constituted a carbonization process for carbonizing the PAN-based flameproof fiber by a first carbonization process and a second carbonization process.
第一炭素化工程においては、耐炎化繊維の各物性と、温度と、延伸倍率との間に重要な関連があり、これらを制御することにより高強度炭素繊維を製造できることを知得し、先に出願した(特願２００２−２５３８０６)。 In the first carbonization process, it is known that there is an important relationship among the physical properties of the flame-resistant fiber, the temperature, and the draw ratio, and it is possible to produce high-strength carbon fiber by controlling these. (Japanese Patent Application No. 2002-253806).
また、第二炭素化工程を、一次処理と二次処理とに分ける場合、それぞれの処理における繊維の各物性と、温度と、繊維の延伸張力との間に重要な関連があり、これらを制御することにより高強度炭素繊維を製造できることを知得し、続いて出願した(特願２００２−３６８８１０)。 In addition, when the second carbonization process is divided into a primary treatment and a secondary treatment, there is an important relationship between the physical properties of the fiber, the temperature, and the fiber drawing tension in each treatment, and these are controlled. As a result, it was learned that high-strength carbon fibers can be produced, and subsequently filed (Japanese Patent Application No. 2002-368810).
本発明者等は、更に検討を重ねた結果、第二炭素化工程の後工程として更に高温処理するための第三炭素化工程を設けた。この第三炭素化工程において、上記先願発明の製造方法で炭素化した高強度炭素繊維を、更に高温処理することによって、高強度・高弾性の炭素繊維を得ることができることを知得した。即ち、上記先願発明で得られる炭素繊維は、高比重で高強度の炭素繊維であるので、その優位性をもって、更に高温処理しても、元の炭素繊維の優位性が保て、より高強度・高弾性の炭素繊維を得ることができることを知得し、本発明を完成するに到った。 As a result of further studies, the present inventors have provided a third carbonization step for further high-temperature treatment as a subsequent step of the second carbonization step. In this third carbonization step, it was found that high strength carbon fiber having high strength and high elasticity can be obtained by subjecting the high strength carbon fiber carbonized by the production method of the prior invention to further high temperature treatment. That is, since the carbon fiber obtained by the prior invention is a carbon fiber having a high specific gravity and a high strength, the superiority of the original carbon fiber can be maintained even when treated at a higher temperature. It was learned that carbon fibers with high strength and high elasticity could be obtained, and the present invention was completed.
よって、本発明の目的とするところは、上記問題を解決した、緻密、高配向度、高強度且つ高弾性率の炭素繊維の製造方法を提供することにある。 Accordingly, an object of the present invention is to provide a method for producing a carbon fiber having a high density, a high degree of orientation, a high strength, and a high elastic modulus, which has solved the above problems.
上記目的を達成する本発明は、以下に記載のものである。 The present invention for achieving the above object is as follows.
〔１〕 不活性雰囲気中で、第一炭素化工程において、比重１．３〜１．４のポリアクリロニトリル系耐炎化繊維を３００〜９００℃の温度範囲内で、１．０３〜１．０６の延伸倍率で一次延伸処理し、次いで０．９〜１．０１の延伸倍率で二次延伸処理した後、第二炭素化工程において８００〜１８００℃の温度範囲内で熱処理して得られた第二炭素化処理繊維を、更に第三炭素化工程において不活性雰囲気中で１８００〜２５００℃の温度範囲内で熱処理する炭素繊維の製造方法において、第一炭素化工程における一次延伸処理を下記条件(１)乃至(３)のいずれをも満たす範囲で行い、二次延伸処理を下記条件(４)、(５)の両方を満たす範囲で行い、引き続き、第二炭素化工程における一次処理として下記条件(６)乃至(１０)のいずれをも満たす範囲で(１１)の延伸処理を行い、次いで二次処理として下記条件(１２)乃至(１４)のいずれをも満たす範囲で(１５)の延伸処理を行い、更に、第三炭素化工程において前記条件で熱処理する炭素繊維の製造方法。
第一炭素化工程条件
一次延伸条件
(１) ポリアクリロニトリル系耐炎化繊維の弾性率が極小値まで低下した時点から９．８ＧＰａに増加するまでの範囲
(２) ポリアクリロニトリル系耐炎化繊維の比重が１．５に達するまでの範囲
(３) ポリアクリロニトリル系耐炎化繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４５ｎｍに達するまでの範囲
二次延伸条件
(４) 一次延伸処理後の繊維の比重が二次延伸処理中に上昇し続ける範囲
(５) 一次延伸処理後の繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４５ｎｍより大きくならない範囲
第二炭素化工程条件
一次処理条件
(６) 第一炭素化処理繊維の比抵抗値が４００Ω・ｇ／ｍ2以上の範囲
(７) 第一炭素化処理繊維の比重が一次処理中上昇し続ける範囲
(８) 第一炭素化処理繊維の窒素含有量が１０質量％以上の範囲
(９) 第一炭素化処理繊維の広角Ｘ線測定(回折角２６°)における配向度が８０．８％以下で、一次処理中上昇し続ける範囲
(１０) 第一炭素化処理繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４７ｎｍより大きくならない範囲
(１１) 第二炭素化工程一次処理での繊維張力(Ｆ ＭＰａ)と第一炭素化処理繊維の断面積(Ｓ ｍｍ2)とで算出される繊維応力(Ｄ ｍＮ)が下式
１．２４ ＞ Ｄ ＞ ０．４６
〔但し、Ｄ ＝ Ｆ × Ｓ
Ｓ ＝ πＡ2 ／ ４
Ａは第一炭素化処理繊維の直径(ｍｍ)〕
を満たす範囲で繊維張力を与える延伸処理
二次処理条件
(１２) 一次処理繊維の比抵抗値が４００Ω・ｇ／ｍ2未満の範囲
(１３) 一次処理繊維の比重が変化しない又は低下する範囲
(１４) 一次処理繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４７ｎｍより大きく、且つ二次処理中上昇し続ける又は変化しない範囲
(１５) 第二炭素化工程二次処理での繊維張力(Ｇ ＭＰａ)と第一炭素化処理繊維の断面積(Ｓ ｍｍ2)とで算出される繊維応力(Ｅ ｍＮ)が下式
０．６０ ＞ Ｅ ＞ ０．２３
〔但し、Ｅ ＝ Ｇ × Ｓ
Ｓ ＝ πＡ2 ／ ４
Ａは第一炭素化処理繊維の直径(ｍｍ)〕
を満たす範囲で繊維張力を与える延伸処理
[1] In an inert atmosphere, in the first carbonization step, a polyacrylonitrile-based flameproof fiber having a specific gravity of 1.3 to 1.4 is within a temperature range of 300 to 900 ° C., and 1.03 to 1.06. The first obtained by first stretching at a draw ratio, then second stretched at a draw ratio of 0.9 to 1.01, and then heat-treated in a temperature range of 800 to 1800 ° C. in the second carbonization step. In the method for producing carbon fiber, in which the carbonized fiber is further heat-treated in an inert atmosphere in the temperature range of 1800 to 2500 ° C. in the third carbonization step, the primary stretching treatment in the first carbonization step is performed under the following conditions (1 ) To (3) is performed in a range satisfying both of the following conditions, the secondary stretching treatment is performed in a range satisfying both of the following conditions (4) and (5), and the following conditions ( Satisfies any of 6) to (10) (11) is stretched within the range, and then, as a secondary treatment, (15) is stretched within a range that satisfies any of the following conditions (12) to (14). A method for producing carbon fiber, which is heat-treated under the above conditions.
First carbonization process condition Primary stretching condition
(1) Range from the time when the elastic modulus of the polyacrylonitrile-based flameproof fiber decreases to a minimum value until it increases to 9.8 GPa
(2) Range until the specific gravity of the polyacrylonitrile-based flameproof fiber reaches 1.5
(3) Range of secondary stretching conditions until the crystallite size reaches 1.45 nm in wide angle X-ray measurement (diffraction angle 26 °) of polyacrylonitrile-based flameproof fiber
(4) Range in which the specific gravity of the fiber after the primary stretching process continues to rise during the secondary stretching process
(5) Range in which the crystallite size is not larger than 1.45 nm in the wide-angle X-ray measurement (diffraction angle 26 °) of the fiber after the primary stretching treatment.
(6) The range of the specific resistance value of the first carbonized fiber is 400Ω · g / m 2 or more.
(7) Range in which the specific gravity of the first carbonized fiber continues to rise during the primary treatment
(8) The range in which the nitrogen content of the first carbonized fiber is 10% by mass or more
(9) The extent of orientation of the first carbonized fiber in the wide-angle X-ray measurement (diffraction angle 26 °) is 80.8% or less and continues to rise during the primary treatment
(10) The range in which the crystallite size of the first carbonized fiber is not larger than 1.47 nm in wide-angle X-ray measurement (diffraction angle 26 °)
(11) The fiber stress (D mN) calculated from the fiber tension (F MPa) in the first treatment in the second carbonization step and the cross-sectional area (S mm 2 ) of the first carbonized fiber is expressed by the following formula 1.24. >D> 0.46
[However, D = F x S
S = πA 2/4
A is the diameter of the first carbonized fiber (mm)]
Secondary treatment conditions for drawing treatment to give fiber tension within the range
(12) The specific resistance value of the primary treated fiber is less than 400Ω · g / m 2
(13) Range in which the specific gravity of the primary treated fiber does not change or decreases
(14) The range in which the crystallite size in the wide-angle X-ray measurement (diffraction angle 26 °) of the primary treated fiber is larger than 1.47 nm and continues to rise or does not change during the secondary treatment
(15) The fiber stress (E mN) calculated from the fiber tension (G MPa) in the second carbonization step secondary treatment and the cross-sectional area (S mm 2 ) of the first carbonized fiber is expressed by the following equation: 60>E> 0.23
[However, E = G × S
S = πA 2/4
A is the diameter of the first carbonized fiber (mm)]
Drawing process that gives fiber tension within the range
本発明の製造方法によれば、第一炭素化工程及び第二炭素化工程において繊維の各種物性を参照して炭素化処理を行って得られた高強度炭素繊維を、第三炭素化工程において更に高温処理しているので、緻密、高配向度、高強度且つ高弾性率の炭素繊維を得ることができる。 According to the production method of the present invention, high-strength carbon fibers obtained by performing carbonization treatment with reference to various physical properties of fibers in the first carbonization step and the second carbonization step are used in the third carbonization step. Furthermore, since it is processed at a high temperature, a carbon fiber having a high density, a high degree of orientation, a high strength and a high elastic modulus can be obtained.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
本発明の炭素繊維の製造方法に用いるＰＡＮ系前駆体繊維は、アクリロニトリルを９０質量％以上、好ましくは９５質量％以上含有する単量体を重合した紡糸溶液を湿式又は乾湿式紡糸法において紡糸した後、水洗・乾燥・延伸して得られる繊維を用いることが好ましい。これらの前駆体繊維は、従来公知のものが何ら制限なく使用できる。 The PAN precursor fiber used in the carbon fiber production method of the present invention is obtained by spinning a spinning solution obtained by polymerizing a monomer containing acrylonitrile in an amount of 90% by mass or more, preferably 95% by mass in a wet or dry wet spinning method. Thereafter, it is preferable to use fibers obtained by washing, drying and stretching. As these precursor fibers, conventionally known fibers can be used without any limitation.
得られた前駆体繊維は、引き続き加熱空気中２００〜２８０℃で耐炎化処理される。この時の処理は、一般的に、延伸倍率０．８５〜１．３０の範囲で処理され、繊維比重１．３〜１．５のＰＡＮ系耐炎化繊維とするものであり、耐炎化時の張力(延伸配分)は特に限定されるものでは無い。 The obtained precursor fiber is subsequently flameproofed at 200 to 280 ° C. in heated air. The treatment at this time is generally a PAN-based flameproof fiber having a fiber specific gravity of 1.3 to 1.5, which is treated in a range of draw ratio of 0.85 to 1.30. The tension (stretch distribution) is not particularly limited.
本発明の炭素繊維の製造方法においては、上記耐炎化繊維を、不活性雰囲気中で、第一炭素化工程において、３００〜９００℃の温度範囲内で、１．０３〜１．０６の延伸倍率で一次延伸処理し、次いで０．９〜１．０１の延伸倍率で二次延伸処理して繊維比重１．５０〜１．７０の第一炭素化処理繊維を得る。 In the carbon fiber manufacturing method of the present invention, the flame-resistant fiber is stretched at a draw ratio of 1.03 to 1.06 within a temperature range of 300 to 900 ° C. in the first carbonization step in an inert atmosphere. Is subjected to a primary stretching treatment, followed by a secondary stretching treatment at a stretching ratio of 0.9 to 1.01 to obtain a first carbonized fiber having a fiber specific gravity of 1.50 to 1.70.
この第一炭素化処理繊維を、不活性雰囲気中で、第二炭素化工程において８００〜１８００℃の温度範囲内で、同工程を一次処理と二次処理とに分けて延伸処理して第二炭素化処理繊維を得る。 The first carbonized fiber is stretched in an inert atmosphere in a second carbonization step within a temperature range of 800 to 1800 ° C. by dividing the step into a primary treatment and a secondary treatment. Carbonized fiber is obtained.
この第二炭素化処理繊維を、不活性雰囲気中で、第三炭素化工程において１８００〜２５００℃の温度範囲内で熱処理する。 This second carbonized fiber is heat-treated in an inert atmosphere within a temperature range of 1800 to 2500 ° C. in the third carbonization step.
上記第一炭素化工程において、一次延伸処理では、ＰＡＮ系耐炎化繊維の弾性率が極小値まで低下した時点から９．８ＧＰａ(１．０ｔｆ／ｍｍ2)に増加するまでの範囲、同繊維の比重が１．５に達するまでの範囲、且つ同繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４５ｎｍに達するまでの範囲で、１．０３〜１．０６の延伸倍率で、延伸処理を行う。 In the first carbonization step, in the primary drawing treatment, the range from the time when the elastic modulus of the PAN-based flameproof fiber is reduced to a minimum value to 9.8 GPa (1.0 tf / mm 2 ), A draw ratio of 1.03 to 1.06 in the range until the specific gravity reaches 1.5 and the crystallite size in the wide-angle X-ray measurement (diffraction angle 26 °) of the same fiber reaches 1.45 nm. Then, a stretching process is performed.
上記のＰＡＮ系耐炎化繊維弾性率が極小値まで低下した時点から９．８ＧＰａに増加するまでの範囲は、図１に示すＢの範囲である。 The range from when the PAN-based flameproof fiber elastic modulus decreases to the minimum value until it increases to 9.8 GPa is the range B shown in FIG.
耐炎化繊維の弾性率が極小値まで低下した時点から９．８ＧＰａに増加するまでの範囲で延伸(１．０３〜１．０６倍)を行うことにより、糸切れを抑制し、低弾性率部が効率的に延伸され高配向化が可能となり、緻密な一次延伸処理繊維を得ることができる。 By performing stretching (1.03 to 1.06 times) in the range from the point when the elastic modulus of the flame resistant fiber decreases to a minimum value until it increases to 9.8 GPa, the yarn breakage is suppressed, and the low elastic modulus part Can be efficiently drawn and highly oriented, and a dense primary drawn fiber can be obtained.
これに対し、弾性率が極小値に低下する前(Ａの範囲)での１．０３倍以上の延伸は、糸切れを増加させ、著しい強度低下を招くので好ましくない。 On the other hand, stretching of 1.03 times or more before the elastic modulus decreases to the minimum value (range A) is not preferable because it increases yarn breakage and causes a significant decrease in strength.
また、弾性率が極小値まで低下し、次いで９．８ＧＰａに増加した後(Ｃの範囲)での１．０３倍以上の延伸は、繊維の弾性率が高く、無理な延伸を強いるので、繊維欠陥・ボイドを増加させ、延伸の効果を損なうので好ましくない。よって、上記弾性率の範囲内で一次延伸処理を行う。 In addition, stretching of 1.03 times or more after the elastic modulus decreases to a minimum value and then increases to 9.8 GPa (range C) is high because the elastic modulus of the fiber is high and excessive stretching is forced. This is undesirable because it increases defects and voids and impairs the effect of stretching. Therefore, the primary stretching process is performed within the above elastic modulus range.
耐炎化繊維の比重が１．５に達するまでの範囲で延伸(１．０３〜１．０６倍)を行うことにより、ボイドの生成を抑制しながら、配向度の向上が出来、高品位の一次延伸処理繊維を得ることができる。 By stretching (1.03 to 1.06 times) until the specific gravity of the flameproofing fiber reaches 1.5, the degree of orientation can be improved while suppressing the generation of voids, and high quality primary. A drawn fiber can be obtained.
これに対し、比重が１．５より高い範囲での１．０３倍以上の一次延伸は、無理な延伸によりボイドの生成を増長し、最終的な炭素繊維の構造欠陥、比重低下を招くため好ましくない。よって、上記比重の範囲内で一次延伸処理を行う。 On the other hand, primary stretching of 1.03 times or more in a range where the specific gravity is higher than 1.5 is preferable because the formation of voids is increased by excessive stretching, resulting in a structural defect and a decrease in specific gravity of the final carbon fiber. Absent. Therefore, the primary stretching process is performed within the range of the specific gravity.
ＰＡＮ系耐炎化繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズは、一次延伸処理時の温度上昇につれて増加し続ける。その増加状態は、図２に示されるように結晶子サイズ０．９ｎｍ付近と１．４５ｎｍ付近に変曲点を持つ曲線である。よって前述の、結晶子サイズが１．４５ｎｍに達するまでの範囲は、後の変曲点に達するまでの範囲である。 The crystallite size in the wide-angle X-ray measurement (diffraction angle 26 °) of the PAN-based flameproof fiber continues to increase as the temperature rises during the primary stretching treatment. The increased state is a curve having inflection points in the vicinity of the crystallite size of 0.9 nm and 1.45 nm as shown in FIG. Therefore, the above-described range until the crystallite size reaches 1.45 nm is a range until the later inflection point is reached.
耐炎化繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４５ｎｍに達するまでの範囲で延伸(１．０３〜１．０６倍)を行うことにより、より緻密でボイドの少ない、一次延伸処理繊維を得ることができる。 By performing stretching (1.03 to 1.06 times) until the crystallite size reaches 1.45 nm in the wide-angle X-ray measurement (diffraction angle 26 °) of the flame-resistant fiber, it is denser and has less voids. A primary stretch treated fiber can be obtained.
これに対し、結晶子サイズが１．４５ｎｍに達した後での１．０３倍以上の一次延伸は、無理な延伸により糸切れを発生させるだけではなく、ボイドの発生を招くため、好ましくない。 On the other hand, primary stretching of 1.03 times or more after the crystallite size reaches 1.45 nm is not preferable because it causes not only thread breakage but also generation of voids due to excessive stretching.
また、一次延伸における延伸倍率が１．０３倍未満では、延伸の効果が少なく、高強度の炭素繊維を得ることができないので好ましくない。延伸倍率が１．０６倍より高いと、糸切れを招き、高品位及び高強度の炭素繊維を得ることはできないので好ましくない。 Moreover, if the draw ratio in primary drawing is less than 1.03, it is not preferable because the drawing effect is small and high-strength carbon fibers cannot be obtained. When the draw ratio is higher than 1.06 times, yarn breakage is caused, and high-quality and high-strength carbon fibers cannot be obtained.
上記方法により得られた一次延伸処理繊維は、引き続いて以下の二次延伸処理を施さなければならない。 The primary stretch treated fiber obtained by the above method must be subsequently subjected to the following secondary stretch treatment.
一次延伸処理後の繊維の比重が二次延伸処理中に上昇し続ける範囲、及び一次延伸処理後の繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４５ｎｍより大きくならない範囲で０．９〜１．０１倍の延伸倍率で延伸処理を行わなければならない。 The range in which the specific gravity of the fiber after the primary stretching process continues to rise during the secondary stretching process, and the range in which the crystallite size in the wide-angle X-ray measurement (diffraction angle 26 °) of the fiber after the primary stretching process does not become larger than 1.45 nm The stretching process must be performed at a stretching ratio of 0.9 to 1.01.
二次延伸処理中における一次延伸処理後の繊維の比重は、図３に示されるように温度上昇につれて、変化しない(上昇しない)条件と、上昇し続ける条件と、上昇後下降する条件(二次延伸処理中に繊維比重が低下する条件)とがある。 As shown in FIG. 3, the specific gravity of the fiber after the primary stretching treatment during the secondary stretching treatment does not change (does not rise), continues to rise, and rises and falls (secondary) as the temperature rises. There is a condition that the fiber specific gravity decreases during the stretching process).
これらの条件のうち、一次延伸処理後の繊維の比重が二次延伸処理中に上昇し続ける条件で０．９〜１．０１倍の延伸倍率で延伸処理を行うことにより、好ましくは変化しない区間を含むことなく又は低下することなく上昇し続ける条件で延伸処理を行うことにより、ボイド生成を抑制し、最終的に緻密な炭素繊維を得ることができる。 Among these conditions, the section where the specific gravity of the fiber after the primary stretching treatment continues to rise during the secondary stretching treatment is preferably not changed by performing the stretching treatment at a draw ratio of 0.9 to 1.01 times. By performing the stretching treatment under the condition of continuing to increase without containing or decreasing, void formation can be suppressed and finally a dense carbon fiber can be obtained.
これに対し、二次延伸処理中に繊維比重が低下すると、ボイドの生成を増長し、緻密な炭素繊維を得ることができず、好ましくない。また、二次延伸処理中に繊維比重が変化しない区間を含むと、二次延伸処理の効果が見られないので、好ましくない。よって、二次延伸処理は繊維比重が上昇し続ける範囲である。 On the other hand, if the fiber specific gravity is lowered during the secondary stretching treatment, void formation is increased, and dense carbon fibers cannot be obtained, which is not preferable. In addition, it is not preferable to include a section where the fiber specific gravity does not change during the secondary stretching process because the effect of the secondary stretching process is not observed. Therefore, the secondary stretching treatment is a range in which the fiber specific gravity continues to rise.
また、一次延伸処理後の繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４５ｎｍより大きくならない範囲で０．９〜１．０１倍の延伸倍率で延伸処理を行うことにより、結晶が成長することなく、緻密化され、ボイドの生成も抑制でき、最終的に高い緻密性を有した炭素繊維を得ることができる。 Further, by performing a stretching treatment at a stretching ratio of 0.9 to 1.01 times in a range where the crystallite size in the wide-angle X-ray measurement (diffraction angle 26 °) of the fiber after the primary stretching treatment does not become larger than 1.45 nm. Without being grown, the crystals are densified, the formation of voids can be suppressed, and finally, carbon fibers having high density can be obtained.
これに対し、結晶子サイズが１．４５ｎｍより大きくなる範囲での二次延伸処理は、ボイドの生成を増長すると共に、糸切れによる品位低下を招き、高強度の炭素繊維を得ることができず、好ましくない。よって、二次延伸処理は上記結晶子サイズの範囲内で行う。 On the other hand, the secondary stretching treatment in the range where the crystallite size is larger than 1.45 nm increases the generation of voids and causes a deterioration in quality due to yarn breakage, and a high-strength carbon fiber cannot be obtained. It is not preferable. Therefore, the secondary stretching treatment is performed within the above crystallite size range.
なお、二次延伸処理における延伸倍率が０．９倍未満では、配向度の低下が著しく、高強度の炭素繊維を得ることができないので好ましくない。延伸倍率が１．０１倍より高いと、糸切れを招き、高品位及び高強度の炭素繊維を得ることはできないので好ましくない。よって、二次延伸処理における延伸倍率は０．９〜１．０１の範囲内が好ましい。 In addition, if the draw ratio in the secondary drawing treatment is less than 0.9 times, the degree of orientation is remarkably lowered, and high strength carbon fibers cannot be obtained. When the draw ratio is higher than 1.01, it is not preferable because yarn breakage is caused and high-quality and high-strength carbon fibers cannot be obtained. Therefore, the draw ratio in the secondary stretching treatment is preferably in the range of 0.9 to 1.01.
また、高強度の炭素繊維を得るためには、第一炭素化処理繊維の広角Ｘ線測定(回折角２６°)における配向度が７６．０％以上あることが好ましい。 In order to obtain high-strength carbon fibers, it is preferable that the degree of orientation of the first carbonized fiber in the wide-angle X-ray measurement (diffraction angle 26 °) is 76.0% or more.
７６．０％未満では最終的に高強度の炭素繊維を得ることができないので好ましくない。 If it is less than 76.0%, a high-strength carbon fiber cannot be finally obtained, which is not preferable.
上記のごとくして、第一炭素化工程における耐炎化繊維の一次延伸処理、二次延伸処理は行われ、第一炭素化処理繊維となる。また、上記第一炭素化工程は、一つの炉若しくは二つ以上の炉で、連続的若しくは別々に処理しても差し支えなく、前述の処理条件範囲内での処理によるところであれば何ら問題はない。 As described above, the primary stretching process and the secondary stretching process of the flame-resistant fiber in the first carbonization step are performed to obtain the first carbonized fiber. In addition, the first carbonization step may be processed continuously or separately in one furnace or two or more furnaces, and there is no problem as long as the process is performed within the above-described processing condition range. .
上記第一炭素化処理繊維は引き続き、第二炭素化工程において８００〜１８００℃の温度範囲内で、同工程を一次処理と二次処理とに分けて炭素化処理される。 The first carbonized fiber is subsequently carbonized in the second carbonization step in a temperature range of 800 to 1800 ° C. by dividing the step into a primary treatment and a secondary treatment.
上記第二炭素化工程の一次処理では、第一炭素化処理繊維の比抵抗値が４００Ω・ｇ／ｍ2以上の範囲、同繊維の比重が一次処理中上昇し続ける範囲、同繊維の窒素含有量が１０質量％以上の範囲、同繊維の広角Ｘ線測定(回折角２６°)における配向度が８０．８％以下で、一次処理中上昇し続ける範囲、且つ同繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４７ｎｍより大きくならない範囲で同繊維を延伸処理する。 In the primary treatment of the second carbonization step, the specific resistance value of the first carbonized fiber is in the range of 400 Ω · g / m 2 or more, the specific gravity of the fiber continues to increase during the primary treatment, and the nitrogen content of the fiber The amount is in the range of 10% by mass or more, the degree of orientation in the wide-angle X-ray measurement (diffraction angle 26 °) of the fiber is 80.8% or less, the range that continues to rise during the primary treatment, and the wide-angle X-ray measurement of the fiber ( The fiber is drawn in a range where the crystallite size at a diffraction angle of 26 ° does not become larger than 1.47 nm.
上記第一炭素化処理繊維の第二炭素化工程一次処理における、比抵抗値、比重、窒素含有量、並びに、広角Ｘ線測定(回折角２６°)での配向度及び結晶子サイズの、変化及び条件範囲の一例を、それぞれ図４、５、６、７及び８に示す。 Changes in specific resistance value, specific gravity, nitrogen content, orientation degree and crystallite size in wide-angle X-ray measurement (diffraction angle 26 °) in the second carbonization step primary treatment of the first carbonized fiber. Examples of the condition ranges are shown in FIGS. 4, 5, 6, 7 and 8, respectively.
なお、第二炭素化工程一次処理での繊維張力(Ｆ ＭＰａ)は、第一炭素化工程後の繊維直径、即ち繊維断面積(Ｓ ｍｍ2)により変わるため、本発明においては張力ファクターとして繊維応力(Ｄ ｍＮ)を用い、この繊維応力の範囲は下式
１．２４ ＞ Ｄ ＞ ０．４６
〔但し、Ｄ ＝ Ｆ × Ｓ
Ｓ ＝ πＡ2 ／ ４
Ａは第一炭素化処理繊維の直径(ｍｍ)〕
を満たす範囲としている。
In addition, since the fiber tension (F MPa) in the second carbonization process primary treatment varies depending on the fiber diameter after the first carbonization process, that is, the fiber cross-sectional area (S mm 2 ), the fiber is used as the tension factor in the present invention. Using stress (D mN), the fiber stress range is: 1.24>D> 0.46
[However, D = F x S
S = πA 2/4
A is the diameter of the first carbonized fiber (mm)]
It is set as the range which satisfies.
ここで繊維断面積は、ＪＩＳ−Ｒ−７６０１に規定する測微顕微鏡による方法において繊維直径をｎ＝２０で測定し、その平均値を用い、真円として算出した値を使用している。 Here, the fiber cross-sectional area uses a value calculated as a perfect circle by measuring the fiber diameter at n = 20 in the method using a microscopic microscope specified in JIS-R-7601 and using the average value.
上記方法により得られた一次処理繊維は、引き続いて以下の二次処理を施す。 The primary treated fiber obtained by the above method is subsequently subjected to the following secondary treatment.
この二次処理においては、一次処理繊維の比抵抗値が４００Ω・ｇ／ｍ2未満の範囲、同繊維の比重が変化しない又は低下する範囲、更に、同繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４７ｎｍより大きく且つ二次処理中上昇し続ける又は変化しない範囲で同繊維を延伸処理する。 In this secondary treatment, the specific resistance value of the primary treated fiber is less than 400 Ω · g / m 2 , the range in which the specific gravity of the fiber does not change or decreases, and further the wide angle X-ray measurement (diffraction angle 26 of the fiber). The fiber is stretched so that the crystallite size at 0) is larger than 1.47 nm and continues to rise or does not change during the secondary treatment.
上記一次処理繊維の二次処理における、比抵抗値、比重、及び広角Ｘ線測定(回折角２６°)での結晶子サイズの、変化及び条件範囲の一例を、それぞれ図９、１０及び１１に示す。 Examples of changes in the specific resistance value, specific gravity, and crystallite size in the wide-angle X-ray measurement (diffraction angle 26 °) and condition range in the secondary treatment of the primary treated fiber are shown in FIGS. Show.
なお、第二炭素化工程二次処理での繊維張力(Ｇ ＭＰａ)も、一次処理時と同様に第一炭素化工程後の繊維直径、即ち繊維断面積(Ｓ ｍｍ2)により変わるため、本発明においては張力ファクターとして繊維応力(Ｅ ｍＮ)を用い、この繊維応力の範囲は下式
０．６０ ＞ Ｅ ＞ ０．２３
〔但し、Ｅ ＝ Ｇ × Ｓ
Ｓ ＝ πＡ2 ／ ４
Ａは第一炭素化処理繊維の直径(ｍｍ)〕
を満たす範囲としている。
Note that the fiber tension (G MPa) in the second carbonization process secondary treatment also varies depending on the fiber diameter after the first carbonization process, that is, the fiber cross-sectional area (S mm 2 ), as in the primary treatment. In the present invention, fiber stress (E mN) is used as a tension factor, and the range of this fiber stress is expressed by the following formula 0.60>E> 0.23.
[However, E = G × S
S = πA 2/4
A is the diameter of the first carbonized fiber (mm)]
It is set as the range which satisfies.
また、第二炭素化処理繊維の伸度は２．２０％以上であることが好ましい。更に、第二炭素化処理繊維の直径は３〜８μｍであることが好ましい。 The elongation of the second carbonized fiber is preferably 2.20% or more. Furthermore, the diameter of the second carbonized fiber is preferably 3 to 8 μm.
この第二炭素化処理繊維は引き続き、不活性雰囲気中で、第三炭素化工程において１８００〜２５００℃の温度範囲内で熱処理される。 The second carbonized fiber is subsequently heat-treated in an inert atmosphere within a temperature range of 1800 to 2500 ° C. in the third carbonization step.
得られた第三炭素化処理繊維、即ち第三炭素化工程終了後に得られる炭素繊維は、引き続き公知の方法により、表面処理を施した炭素繊維となり得る。さらに、炭素繊維の後加工をしやすくし、取扱性を向上させる目的で、サイジング処理することが好ましい。サイジング方法は、従来の公知の方法で行うことができ、サイジング剤は、用途に即して適宜組成を変更して使用し、均一付着させた後に、乾燥することが好ましい。なお、第三炭素化処理繊維の直径は４〜８μmであることが好ましい。 The obtained third carbonized fiber, that is, the carbon fiber obtained after completion of the third carbonization step, can be subsequently subjected to surface treatment by a known method. Furthermore, it is preferable to perform a sizing treatment for the purpose of facilitating the post-processing of the carbon fiber and improving the handleability. The sizing method can be carried out by a conventionally known method, and the sizing agent is preferably used after changing its composition as appropriate according to the application, and after uniformly adhering. In addition, it is preferable that the diameter of a 3rd carbonization processing fiber is 4-8 micrometers.
このようにして得られた炭素繊維は、緻密、高配向度、高強度且つ高弾性率を有し、ストランドの引揃え性が乱れることの無い、良好なストランド形態の炭素繊維であり、本発明の製造方法によりなし得るものである。 The carbon fiber thus obtained is a carbon fiber in a good strand form, having a dense, high orientation degree, high strength and high elastic modulus, and without disturbing the alignment of the strands. This can be achieved by the manufacturing method described above.
以下、本発明を実施例及び比較例により更に具体的に説明する。また、各実施例及び比較例における処理条件、及び炭素繊維物性についての評価方法は以下の方法により実施した。 Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Moreover, the processing conditions in each Example and a comparative example, and the evaluation method about carbon fiber physical property were implemented with the following method.
＜比抵抗値＞
比抵抗値の測定に関しては、ＪＩＳ−Ｒ−７６０１に規定する体積抵抗率の炭素繊維の試験Ａ法を参考に行うことができる。ただし、ＪＩＳ−Ｒ−７６０１では、電気抵抗値に、炭素繊維の比重を掛け合わせた体積抵抗率を求めており、比抵抗値〔Ｘ (Ω・ｇ／ｍ2)〕を求めるには、下式
Ｘ ＝ Ｒｂ×ｔ／Ｌ
Ｒｂ：試験片長Ｌのときの電気抵抗(Ω)、ｔ：試験片の繊度(ｔｅｘ)、Ｌ：抵抗測定時の試験片長(ｍ)
を用いて行った。なお、抵抗測定時の試験片長については、１ｍ程度で測定することが好ましい。
<Specific resistance value>
Regarding the measurement of the specific resistance value, it can be performed with reference to the test method A of the carbon fiber having the volume resistivity specified in JIS-R-7601. However, in JIS-R-7601, the volume resistivity obtained by multiplying the electrical resistance value by the specific gravity of the carbon fiber is obtained. To obtain the specific resistance value [X (Ω · g / m 2 )], Formula X = Rb × t / L
Rb: electrical resistance (Ω) when the test piece length is L, t: fineness (tex) of the test piece, L: test piece length (m) during resistance measurement
It was performed using. In addition, about the test piece length at the time of resistance measurement, it is preferable to measure at about 1 m.
＜比重＞
アルキメデス法により測定した。試料繊維はアセトン中にて脱気処理し測定した。
<Specific gravity>
Measured by Archimedes method. The sample fiber was deaerated in acetone and measured.
＜窒素含有量＞
元素分析装置(ＦＩＳＯＮＳ ＩＮＳＴＲＵＭＥＮＴＳ社製)により測定した元素分析値から求めた。
<Nitrogen content>
It calculated | required from the elemental-analysis value measured with the elemental-analysis apparatus (made by FISON INSTRUMENTS).
＜結晶子サイズ、配向度＞
Ｘ線回折装置：リガク製RINT1200L、コンピュータ：日立2050/32を使用し、回折角２６°における結晶子サイズを回折パターンより、配向度を半価幅より求めた。
<Crystallite size and orientation>
Using X-ray diffractometer: RINT1200L manufactured by Rigaku, computer: Hitachi 2050/32, the crystallite size at a diffraction angle of 26 ° was determined from the diffraction pattern, and the degree of orientation was determined from the half width.
＜単繊維弾性率＞
ＪＩＳ Ｒ ７６０６(２０００)に規定された方法により第一炭素化工程一次延伸処理繊維の単繊維弾性率を測定した。
<Single fiber elastic modulus>
The single fiber elastic modulus of the first carbonized process primary stretch treated fiber was measured by the method defined in JIS R 7606 (2000).
＜ストランド強度、弾性率＞
ＪＩＳ Ｒ ７６０１に規定された方法により第二炭素化処理繊維、第三炭素化処理繊維(炭素繊維)のストランド強度、弾性率を測定した。
<Strand strength, elastic modulus>
The strand strength and elastic modulus of the second carbonized fiber and the third carbonized fiber (carbon fiber) were measured by the method defined in JIS R7601.
実施例１
アクリロニトリル９５質量％／アクリル酸メチル４質量％／イタコン酸１質量％よりなる共重合体紡糸原液を湿式又は乾湿式紡糸し、水洗・乾燥・延伸・オイリングして繊維直径９．１μｍの前駆体繊維を得た。この繊維を加熱空気中、入口温度(最低温度)２００℃、出口温度(最高温度)２６０℃の熱風循環式耐炎化炉で耐炎化処理し、繊維比重１．３４のＰＡＮ系耐炎化繊維を得た。
Example 1
A precursor fiber having a fiber diameter of 9.1 μm is obtained by wet or dry-wet spinning of a copolymer spinning solution of 95% by weight of acrylonitrile / 4% by weight of methyl acrylate / 1% by weight of itaconic acid, followed by washing with water, drying, drawing and oiling. Got. This fiber is flameproofed in heated air in a hot air circulation type flameproofing furnace having an inlet temperature (minimum temperature) of 200 ° C. and an outlet temperature (maximum temperature) of 260 ° C. to obtain a PAN-based flameproofing fiber having a fiber specific gravity of 1.34. It was.
次いで、この耐炎化繊維を不活性雰囲気中、入口温度(最低温度)３００℃、出口温度(最高温度)８００℃の第一炭素化炉において、一次延伸・二次延伸処理を表１に示す条件で実施した。 Next, this flame-resistant fiber was subjected to the conditions shown in Table 1 for primary stretching and secondary stretching in an inert atmosphere in a first carbonization furnace having an inlet temperature (minimum temperature) of 300 ° C. and an outlet temperature (maximum temperature) of 800 ° C. It carried out in.
一次延伸は図１のＢの範囲内で、延伸倍率１．０５倍で処理した。この一次延伸処理後の繊維、即ち一次延伸処理繊維は、単繊維弾性率８．８ＧＰａ、比重１．４０、結晶子サイズ１．２０ｎｍの、糸切れのない繊維であった。 The primary stretching was performed at a stretching ratio of 1.05 within the range of B in FIG. The fiber after the primary stretching treatment, that is, the primary stretch-treated fiber was a fiber having a single fiber elastic modulus of 8.8 GPa, a specific gravity of 1.40 and a crystallite size of 1.20 nm and having no yarn breakage.
その後この一次延伸処理繊維を、引き続き第一炭素化工程において、二次延伸が終了するまで比重が上昇し続ける範囲、且つ結晶子サイズが１．４５ｎｍより大きくならない範囲で、延伸倍率１．００倍で二次延伸処理したところ、比重１．７０、配向度７９．２％、繊維直径５．９μｍ、繊維断面積２．７３×１０-5ｍｍ2の、糸切れのない第一炭素化処理繊維を得た。 Thereafter, the primary stretched fiber is continuously stretched in the first carbonization step in a range where the specific gravity continues to increase until the secondary stretching is completed, and the crystallite size does not become larger than 1.45 nm, and the draw ratio is 1.00 times. The first carbonized fiber having a specific gravity of 1.70, an orientation degree of 79.2%, a fiber diameter of 5.9 μm, and a fiber cross-sectional area of 2.73 × 10 −5 mm 2 without breakage. Got.
次いで、この第一炭素化処理繊維を不活性雰囲気中、入口温度(最低温度)８００℃、出口温度(最高温度)１７００℃の第二炭素化炉において、一次処理・二次処理を以下に示す条件で実施した。 Next, primary treatment and secondary treatment of the first carbonized fiber in an inert atmosphere in a second carbonization furnace having an inlet temperature (minimum temperature) of 800 ° C. and an outlet temperature (maximum temperature) of 1700 ° C. are shown below. Conducted under conditions.
先ず、上記第一炭素化処理繊維を、比抵抗値、比重、窒素含有量、配向度、及び結晶子サイズについて、図４、５、６、７及び８に示す範囲内に調節すると共に、繊維張力２９．９ＭＰａ、繊維応力０．８１７ｍＮで延伸処理し、一次処理繊維を得た。 First, the first carbonized fiber is adjusted to have a specific resistance value, specific gravity, nitrogen content, orientation degree, and crystallite size within the ranges shown in FIGS. The fiber was stretched at a tension of 29.9 MPa and a fiber stress of 0.817 mN to obtain a primary treated fiber.
その後この一次処理繊維を、引き続き第二炭素化工程において二次処理が終了するまで、比抵抗値、比重、及び結晶子サイズについて、図９、１０及び１１に示す範囲内に調節すると共に、繊維張力１４．９ＭＰａ、繊維応力０．４０８ｍＮで延伸処理し、比重１．８１０、繊維直径５．０μｍ、ストランド強度６５００ＭＰａ、ストランド弾性率２８０ＧＰａ、配向度８２．０％、結晶子サイズ１．９０ｎｍの第二炭素化処理繊維を得た。 Thereafter, the primary treated fiber is adjusted within the ranges shown in FIGS. 9, 10 and 11 for the specific resistance value, specific gravity and crystallite size until the secondary treatment is subsequently completed in the second carbonization step. Stretched with a tension of 14.9 MPa and a fiber stress of 0.408 mN, a specific gravity of 1.810, a fiber diameter of 5.0 μm, a strand strength of 6500 MPa, a strand elastic modulus of 280 GPa, an orientation degree of 82.0%, and a crystallite size of 1.90 nm. A dicarbonized fiber was obtained.
次いで、この第二炭素化処理繊維を不活性雰囲気中、入口温度(最低温度)１８００℃、出口温度(最高温度)２３００℃の第三炭素化炉において熱処理し、第三炭素化処理繊維を得た。 The second carbonized fiber is then heat-treated in an inert atmosphere in a third carbonization furnace at an inlet temperature (minimum temperature) of 1800 ° C. and an outlet temperature (maximum temperature) of 2300 ° C. to obtain a third carbonized fiber. It was.
更に、この第三炭素化処理繊維を引き続き公知の方法にて表面処理、サイジングを施し、乾燥して比重１．７９０、繊維直径４．９μｍ、ストランド強度５８００ＭＰａ、ストランド弾性率３６０ＧＰａ、配向度８５．８％、結晶子サイズ２．７０ｎｍの炭素繊維を得た。 Further, the third carbonized fiber was subsequently subjected to surface treatment and sizing by a known method, and dried to have a specific gravity of 1.790, a fiber diameter of 4.9 μm, a strand strength of 5800 MPa, a strand elastic modulus of 360 GPa, and an orientation degree of 85. Carbon fiber having 8% crystallite size of 2.70 nm was obtained.
実施例２
表１に示すように、実施例１で得られた耐炎化繊維について、第一炭素化工程における一次延伸処理を、延伸倍率１．０６倍で行い、単繊維弾性率８．４ＧＰａ、比重１．３９、結晶子サイズ１．１０ｎｍの糸切れのない一次延伸処理繊維を得た。この処理繊維についての二次延伸処理を、二次延伸が終了するまで比重が実施例１よりも急勾配で上昇し続ける範囲、且つ結晶子サイズが１．４５ｎｍより大きくならない範囲で、延伸倍率１．０１倍で行い、比重１．７５、配向度８０．０％、繊維直径５．５μｍの、糸切れの無い二次延伸処理繊維を得た。
Example 2
As shown in Table 1, the flame-resistant fibers obtained in Example 1 were subjected to a primary stretching treatment in the first carbonization step at a stretching ratio of 1.06, a single fiber elastic modulus of 8.4 GPa, and a specific gravity of 1. 39, a primary drawn fiber having a crystallite size of 1.10 nm and no yarn breakage was obtained. In the secondary stretching treatment for this treated fiber, the stretching ratio is 1 in a range where the specific gravity continues to rise more steeply than Example 1 until the secondary stretching is completed, and the crystallite size does not become larger than 1.45 nm. This was performed at 0.01 times to obtain a secondary stretch-treated fiber having a specific gravity of 1.75, an orientation degree of 80.0%, and a fiber diameter of 5.5 μm and having no yarn breakage.
次いで、この第一炭素化処理繊維を第二炭素化工程一次処理において、繊維張力４４．７ＭＰａ、繊維応力１．０６２ｍＮで処理し、第二炭素化工程二次処理において、繊維張力１５．５ＭＰａ、繊維応力０．３６８ｍＮで処理し、比重１．８２０、繊維直径５．０μｍ、ストランド強度６６００ＭＰａ、ストランド弾性率２７９ＧＰａ、配向度８１．８％、結晶子サイズ１．８８ｎｍの第二炭素化処理繊維を得た。 Next, the first carbonized fiber is treated with a fiber tension of 44.7 MPa and a fiber stress of 1.062 mN in the second carbonization step primary treatment, and in the second carbonization step secondary treatment, the fiber tension is 15.5 MPa. Treated with a fiber stress of 0.368 mN, a second carbonized fiber having a specific gravity of 1.820, a fiber diameter of 5.0 μm, a strand strength of 6600 MPa, a strand elastic modulus of 279 GPa, an orientation degree of 81.8%, and a crystallite size of 1.88 nm. Obtained.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して比重１．７９５、繊維直径４．９μｍ、ストランド強度５８２０ＭＰａ、ストランド弾性率３５８ＧＰａ、配向度８５．７％、結晶子サイズ２．７０ｎｍの炭素繊維を得た。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then surface-treated, sized, and dried to have a specific gravity of 1.795, a fiber diameter of 4.9 μm, and a strand strength. A carbon fiber having 5820 MPa, a strand elastic modulus of 358 GPa, an orientation degree of 85.7%, and a crystallite size of 2.70 nm was obtained.
実施例３
表１に示すように、実施例１で得られた第一炭素化工程一次延伸処理繊維を、第一炭素化工程二次延伸処理において、二次延伸が終了するまで比重が実施例１よりも緩勾配で上昇し続ける範囲、且つ結晶子サイズが１．４５ｎｍより大きくならない範囲で、延伸倍率１．００倍で行い、比重１．５２、配向度７７．１％、繊維直径６．８μｍの、糸切れの無い二次延伸処理繊維を得た。
Example 3
As shown in Table 1, the first carbonization step primary stretched fiber obtained in Example 1 has a specific gravity higher than that of Example 1 until the secondary stretch is completed in the first carbonization step secondary stretch treatment. In a range that continues to rise with a gentle gradient, and in a range where the crystallite size does not become larger than 1.45 nm, the stretching ratio is 1.00 times, the specific gravity is 1.52, the degree of orientation is 77.1%, and the fiber diameter is 6.8 μm. A secondary stretch-treated fiber without thread breakage was obtained.
次いで、この第一炭素化処理繊維を、第二炭素化工程一次処理において繊維張力１８．０ＭＰａ、繊維応力０．６５３ｍＮで処理し、第二炭素化工程二次処理において、繊維張力１１．２ＭＰａ、繊維応力０．４０８ｍＮで処理し、比重１．８００、繊維直径５．０μｍ、ストランド強度６４００ＭＰａ、ストランド弾性率２８０ＧＰａ、配向度８１．７％、結晶子サイズ１．８６ｎｍの第二炭素化処理繊維を得た。 Next, the first carbonized fiber is treated with a fiber tension of 18.0 MPa and a fiber stress of 0.653 mN in the second carbonization step primary treatment, and in the second carbonization step secondary treatment, the fiber tension is 11.2 MPa. Treated with a fiber stress of 0.408 mN, a second carbonized fiber having a specific gravity of 1.800, a fiber diameter of 5.0 μm, a strand strength of 6400 MPa, a strand elastic modulus of 280 GPa, an orientation degree of 81.7%, and a crystallite size of 1.86 nm. Obtained.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して比重１．７８５、繊維直径４．９μｍ、ストランド強度５５００ＭＰａ、ストランド弾性率３６５ＧＰａ、配向度８５．９％、結晶子サイズ２．７５ｎｍの炭素繊維を得た。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then surface-treated, sized, and dried to have a specific gravity of 1.785, a fiber diameter of 4.9 μm, and a strand strength. A carbon fiber having 5500 MPa, a strand elastic modulus of 365 GPa, an orientation degree of 85.9%, and a crystallite size of 2.75 nm was obtained.
比較例１
表１に示すように、実施例１で得られた第一炭素化処理繊維を、第二炭素化工程一次処理において、繊維張力５０．８ＭＰａ、繊維応力１．３８８ｍＮで処理した以外は実施例１と同様の処理を行った。しかし、得られた第二炭素化処理繊維は、比重１．７９４、繊維直径４．９μｍ、ストランド強度６１５０ＭＰａ、ストランド弾性率２８５ＧＰａ、配向度８２．１％、結晶子サイズ１．９０ｎｍと、低強度のものであった。
Comparative Example 1
As shown in Table 1, Example 1 except that the first carbonized fiber obtained in Example 1 was treated with a fiber tension of 50.8 MPa and a fiber stress of 1.388 mN in the primary treatment of the second carbonization process. The same process was performed. However, the obtained second carbonized fiber has a specific gravity of 1.794, a fiber diameter of 4.9 μm, a strand strength of 6150 MPa, a strand elastic modulus of 285 GPa, an orientation degree of 82.1%, and a crystallite size of 1.90 nm. It was a thing.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して炭素繊維を得た。しかし、得られた炭素繊維は、比重１．７７３、繊維直径４．８μｍ、ストランド強度５１００ＭＰａ、ストランド弾性率３６７ＧＰａ、配向度８６．１％、結晶子サイズ２．７２ｎｍと、低強度のものであった。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then subjected to surface treatment and sizing, and dried to obtain a carbon fiber. However, the obtained carbon fiber has a low strength such as a specific gravity of 1.773, a fiber diameter of 4.8 μm, a strand strength of 5100 MPa, a strand elastic modulus of 367 GPa, an orientation degree of 86.1%, and a crystallite size of 2.72 nm. It was.
比較例２
表２に示すように、実施例１で得られた第一炭素化処理繊維を、第二炭素化工程一次処理において、繊維張力１４．９ＭＰａ、繊維応力０．４０８ｍＮで処理した以外は実施例１と同様の処理を行った。しかし、得られた第二炭素化処理繊維は、比重１．８０３、繊維直径５．２μｍ、ストランド強度６２００ＭＰａ、ストランド弾性率２８１ＧＰａ、配向度８１．４％、結晶子サイズ１．８９ｎｍと、低強度のものであった。
Comparative Example 2
As shown in Table 2, Example 1 except that the first carbonized fiber obtained in Example 1 was treated with a fiber tension of 14.9 MPa and a fiber stress of 0.408 mN in the primary treatment of the second carbonization process. The same process was performed. However, the obtained second carbonized fiber has a specific gravity of 1.803, a fiber diameter of 5.2 μm, a strand strength of 6200 MPa, a strand elastic modulus of 281 GPa, an orientation degree of 81.4%, and a crystallite size of 1.89 nm. It was a thing.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して炭素繊維を得た。しかし、得られた炭素繊維は、比重１．７８２、繊維直径５．０μｍ、ストランド強度５３００ＭＰａ、ストランド弾性率３６０ＧＰａ、配向度８５．６％、結晶子サイズ２．７４ｎｍと、低強度のものであった。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then subjected to surface treatment and sizing, and dried to obtain a carbon fiber. However, the obtained carbon fiber had a specific gravity of 1.782, a fiber diameter of 5.0 μm, a strand strength of 5300 MPa, a strand elastic modulus of 360 GPa, an orientation degree of 85.6%, and a crystallite size of 2.74 nm. It was.
比較例３
表２に示すように、実施例１で得られた第一炭素化処理繊維を、第二炭素化工程二次処理において、繊維張力２３．９ＭＰａ、繊維応力０．６５３ｍＮで処理した以外は実施例１と同様の処理を行った。しかし、得られた第二炭素化処理繊維は、比重１．８０４、繊維直径４．９μｍ、ストランド強度６３２０ＭＰａ、ストランド弾性率２８７ＧＰａ、配向度８２．２％、結晶子サイズ１．９１ｎｍと、低強度のものであった。
Comparative Example 3
As shown in Table 2, Example 1 except that the first carbonized fiber obtained in Example 1 was treated with a fiber tension of 23.9 MPa and a fiber stress of 0.653 mN in the second carbonization process secondary treatment. 1 was performed. However, the obtained second carbonized fiber has a specific gravity of 1.804, a fiber diameter of 4.9 μm, a strand strength of 6320 MPa, a strand elastic modulus of 287 GPa, an orientation degree of 82.2%, a crystallite size of 1.91 nm, and a low strength. It was a thing.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して炭素繊維を得た。しかし、得られた炭素繊維は、比重１．７８０、繊維直径４．８μｍ、ストランド強度５３５０ＭＰａ、ストランド弾性率３６７ＧＰａ、配向度８６．１％、結晶子サイズ２．７６ｎｍと、低強度のものであった。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then subjected to surface treatment and sizing, and dried to obtain a carbon fiber. However, the carbon fiber obtained had a low strength of a specific gravity of 1.780, a fiber diameter of 4.8 μm, a strand strength of 5350 MPa, a strand elastic modulus of 367 GPa, an orientation degree of 86.1%, and a crystallite size of 2.76 nm. It was.
比較例４
表２に示すように、実施例１で得られた第一炭素化処理繊維を、第二炭素化工程二次処理において、繊維張力６．０ＭＰａ、繊維応力０．１６３ｍＮで処理した以外は実施例１と同様の処理を行った。得られた第二炭素化処理繊維の物性は、比重１．８０８、繊維直径５．１μｍ、ストランド強度６４００ＭＰａ、ストランド弾性率２７９ＧＰａ、配向度８１．８％、結晶子サイズ１．８９ｎｍであった。
Comparative Example 4
As shown in Table 2, the first carbonized fiber obtained in Example 1 was treated in the second carbonization step secondary treatment except that it was treated with a fiber tension of 6.0 MPa and a fiber stress of 0.163 mN. 1 was performed. The physical properties of the obtained second carbonized fiber were a specific gravity of 1.808, a fiber diameter of 5.1 μm, a strand strength of 6400 MPa, a strand elastic modulus of 279 GPa, an orientation degree of 81.8%, and a crystallite size of 1.89 nm.
しかし、この第二炭素化処理繊維のストランド形態は、ストランドの引揃え性が乱れており纏りの無い悪い形態であり、第三炭素化炉における熱処理に移れるものではなかった。 However, the strand form of this second carbonized fiber is a bad form with disordered strand alignment and cannot be transferred to heat treatment in a third carbonization furnace.
比較例５
表２に示すように、第一炭素化工程における一次延伸処理を、図１のＡの範囲内で、延伸倍率１．０５倍で処理し、単繊維弾性率９．２ＧＰａ、比重１．３７、結晶子サイズ０．９０ｎｍの一次延伸処理繊維を得た以外は実施例１と同様の処理を行った。しかし、この一次延伸処理から二次延伸処理に移ったところ、糸切れが多く発生し、二次延伸不可能であった。
Comparative Example 5
As shown in Table 2, the primary stretching process in the first carbonization step was performed at a stretching ratio of 1.05 times within the range of A in FIG. 1 to obtain a single fiber elastic modulus of 9.2 GPa, a specific gravity of 1.37, The same treatment as in Example 1 was performed except that a primary stretch treated fiber having a crystallite size of 0.90 nm was obtained. However, when the primary stretching process was shifted to the secondary stretching process, many yarn breaks occurred and the secondary stretching was impossible.
比較例６
表３に示すように、第一炭素化工程における一次延伸処理を、図１のＣの範囲内で、延伸倍率１．０５倍で処理し、単繊維弾性率１０．３ＧＰａ、比重１．５２、結晶子サイズ１．４５ｎｍの一次延伸処理繊維を得た以外は実施例１と同様の処理を行った。しかし、この一次延伸処理から二次延伸処理に移ったところ、糸切れが多く発生し、二次延伸不可能であった。
Comparative Example 6
As shown in Table 3, the primary stretching process in the first carbonization step was performed at a stretching ratio of 1.05 times within the range of C in FIG. 1 to obtain a single fiber elastic modulus of 10.3 GPa, a specific gravity of 1.52, The same treatment as in Example 1 was performed except that a primary stretch treated fiber having a crystallite size of 1.45 nm was obtained. However, when the primary stretching process was shifted to the secondary stretching process, many yarn breaks occurred and the secondary stretching was impossible.
比較例７
表３に示すように、第一炭素化工程における二次延伸処理を、二次延伸が終了するまでにおいて比重が上昇した後下降する範囲、且つ結晶子サイズが１．４７ｎｍとなる範囲で、延伸倍率１．００倍で行い、比重１．８０、配向度８０．１％、繊維直径５．４μｍの、糸切れのない二次延伸処理繊維を得、次いで、この処理繊維を第二炭素化処理した以外は実施例１と同様の処理を行った。しかし、得られた第二炭素化処理繊維は、比重１．８００、繊維直径５．０μｍ、ストランド強度６０５０ＭＰａ、ストランド弾性率２８５ＧＰａ、配向度８２．１％、結晶子サイズ１．９０ｎｍと、低強度のものであった。
Comparative Example 7
As shown in Table 3, the secondary stretching process in the first carbonization step is performed in such a range that the specific gravity increases and then decreases until the secondary stretching is completed, and the crystallite size is 1.47 nm. Performed at a magnification of 1.00 times to obtain a secondary stretch-treated fiber having a specific gravity of 1.80, an orientation degree of 80.1%, and a fiber diameter of 5.4 μm and having no yarn breakage. Except that, the same processing as in Example 1 was performed. However, the obtained second carbonized fiber has a specific gravity of 1.800, fiber diameter of 5.0 μm, strand strength of 6050 MPa, strand elastic modulus of 285 GPa, orientation degree of 82.1%, crystallite size of 1.90 nm, and low strength. It was a thing.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して炭素繊維を得た。しかし、得られた炭素繊維は、比重１．７７８、繊維直径４．９μｍ、ストランド強度５０００ＭＰａ、ストランド弾性率３６３ＧＰａ、配向度８５．８％、結晶子サイズ２．７５ｎｍと、低強度のものであった。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then subjected to surface treatment and sizing, and dried to obtain a carbon fiber. However, the obtained carbon fiber has a specific gravity of 1.778, a fiber diameter of 4.9 μm, a strand strength of 5000 MPa, a strand elastic modulus of 363 GPa, an orientation degree of 85.8%, and a crystallite size of 2.75 nm. It was.
比較例８
表３に示すように、第一炭素化工程における二次延伸処理を、二次延伸が終了するまでにおいて比重が変化しない(上昇しない)範囲、且つ結晶子サイズが１．４５ｎｍとなる範囲で、延伸倍率１．００倍で行い、比重１．５０、配向度７７．０％、繊維直径６．９μｍの、糸切れのない二次延伸処理繊維を得、次いで、この処理繊維を第二炭素化処理した以外は実施例１と同様の処理を行った。しかし、得られた第二炭素化処理繊維は、比重１．８０５、繊維直径５．０μｍ、ストランド強度６２００ＭＰａ、ストランド弾性率２８０ＧＰａ、配向度８１．９％、結晶子サイズ１．９０ｎｍと、低強度のものであった。
Comparative Example 8
As shown in Table 3, the secondary stretching treatment in the first carbonization step is a range where the specific gravity does not change (does not increase) until the secondary stretching is completed, and the crystallite size is 1.45 nm. Performed at a draw ratio of 1.00 times to obtain a secondary stretch-treated fiber having a specific gravity of 1.50, an orientation degree of 77.0%, and a fiber diameter of 6.9 μm, and without thread breakage. Except for the treatment, the same treatment as in Example 1 was performed. However, the obtained second carbonized fiber has a specific gravity of 1.805, a fiber diameter of 5.0 μm, a strand strength of 6200 MPa, a strand elastic modulus of 280 GPa, an orientation degree of 81.9%, and a crystallite size of 1.90 nm. It was a thing.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して炭素繊維を得た。しかし、得られた炭素繊維は、比重１．７８４、繊維直径４．９μｍ、ストランド強度５３８０ＭＰａ、ストランド弾性率３５８ＧＰａ、配向度８５．５％、結晶子サイズ２．６９ｎｍと、低強度のものであった。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then subjected to surface treatment and sizing, and dried to obtain a carbon fiber. However, the obtained carbon fiber has a low specific strength of 1.784, a fiber diameter of 4.9 μm, a strand strength of 5380 MPa, a strand elastic modulus of 358 GPa, an orientation degree of 85.5%, and a crystallite size of 2.69 nm. It was.
比較例９
表３に示すように、第一炭素化工程における一次延伸倍率を１．０２倍とし、二次延伸処理を、二次延伸が終了するまで比重が上昇し続ける範囲、且つ結晶子サイズが１．４５ｎｍより大きくならない範囲で、延伸倍率１．００倍で行い、比重１．６３、配向度７８．０％、繊維直径６．１μｍの、糸切れのない二次延伸処理繊維を得、次いで、この処理繊維を第二炭素化処理した以外は実施例１と同様の処理を行った。しかし、得られた第二炭素化処理繊維は、比重１．８０４、繊維直径５．１μｍ、ストランド強度６２５０ＭＰａ、ストランド弾性率２７５ＧＰａ、配向度８１．５％、結晶子サイズ１．８９ｎｍと、低強度のものであった。
Comparative Example 9
As shown in Table 3, the primary stretching ratio in the first carbonization step is 1.02 times, and the secondary stretching treatment is performed in a range where the specific gravity continues to rise until the secondary stretching is completed, and the crystallite size is 1. In a range not exceeding 45 nm, a draw ratio of 1.00 is performed to obtain a secondary stretch-treated fiber having a specific gravity of 1.63, an orientation degree of 78.0%, and a fiber diameter of 6.1 μm and having no yarn breakage. The same treatment as in Example 1 was performed except that the treated fiber was subjected to the second carbonization treatment. However, the obtained second carbonized fiber has a specific gravity of 1.804, a fiber diameter of 5.1 μm, a strand strength of 6250 MPa, a strand elastic modulus of 275 GPa, an orientation degree of 81.5%, and a crystallite size of 1.89 nm. It was a thing.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して炭素繊維を得た。しかし、得られた炭素繊維は、比重１．７８１、繊維直径４．９μｍ、ストランド強度５２８０ＭＰａ、ストランド弾性率３５５ＧＰａ、配向度８５．４％、結晶子サイズ２．６８ｎｍと、低強度のものであった。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then subjected to surface treatment and sizing, and dried to obtain a carbon fiber. However, the obtained carbon fiber had a specific gravity of 1.781, a fiber diameter of 4.9 μm, a strand strength of 5280 MPa, a strand elastic modulus of 355 GPa, an orientation degree of 85.4%, and a crystallite size of 2.68 nm. It was.
比較例１０
表４に示すように、第一炭素化工程における一次延伸処理を延伸倍率１．０７倍で行い、糸切れの多い一次延伸処理繊維を得、この処理繊維の二次延伸処理を、二次延伸が終了するまで比重が上昇し続ける範囲、且つ結晶子サイズが１．４５ｎｍより大きくならない範囲で、延伸倍率１．００倍で行い、比重１．６８、配向度７９．３％、繊維直径５．７μｍの、糸切れの多い二次延伸処理繊維を得、次いで、この処理繊維を第二炭素化処理した以外は実施例１と同様の処理を行った。得られた第二炭素化処理繊維の物性は、比重１．７９７、繊維直径４．８μｍ、ストランド強度６４００ＭＰａ、ストランド弾性率２８５ＧＰａ、配向度８２．０％、結晶子サイズ１．９０ｎｍであった。
Comparative Example 10
As shown in Table 4, the primary stretching process in the first carbonization step is performed at a draw ratio of 1.07 to obtain a primary stretched fiber with many yarn breaks, and the secondary stretching process of this treated fiber is performed as a secondary stretch. In the range where the specific gravity continues to rise until the end of the process is completed and the crystallite size does not become larger than 1.45 nm, the drawing is performed at a draw ratio of 1.00, specific gravity 1.68, orientation degree 79.3%,
しかし、この第二炭素化処理繊維のストランド形態は、ストランドの引揃え性が乱れており纏りの無い悪い形態であり、第三炭素化炉における熱処理に移れるものではなかった。 However, the strand form of this second carbonized fiber is a bad form with disordered strand alignment and cannot be transferred to heat treatment in a third carbonization furnace.
比較例１１
表４に示すように、第一炭素化工程における二次延伸処理を、二次延伸が終了するまで比重が上昇し続ける範囲、且つ結晶子サイズが１．４５ｎｍより大きくならない範囲で、延伸倍率０．８５倍で行い、比重１．７１、配向度７９．０％、繊維直径６．０μｍの、糸切れのない二次延伸処理繊維を得、次いで、この処理繊維を第二炭素化処理した以外は実施例１と同様の処理を行った。しかし、得られた第二炭素化処理繊維は、比重１．８０５、繊維直径５．２μｍ、ストランド強度６２５０ＭＰａ、ストランド弾性率２７６ＧＰａ、配向度８１．８％、結晶子サイズ１．９０ｎｍと、低強度のものであった。
Comparative Example 11
As shown in Table 4, the secondary stretching treatment in the first carbonization step is performed in a range where the specific gravity continues to rise until the secondary stretching is completed, and in a range where the crystallite size does not become larger than 1.45 nm. A secondary stretch-treated fiber having a specific gravity of 1.71, an orientation degree of 79.0%, a fiber diameter of 6.0 μm and having no yarn breakage is obtained, and then this treated fiber is subjected to a second carbonization treatment. The same treatment as in Example 1 was performed. However, the obtained second carbonized fiber has a specific gravity of 1.805, a fiber diameter of 5.2 μm, a strand strength of 6250 MPa, a strand elastic modulus of 276 GPa, an orientation degree of 81.8%, a crystallite size of 1.90 nm, and a low strength. It was a thing.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して炭素繊維を得た。しかし、得られた炭素繊維は、比重１．７８２、繊維直径５．０μｍ、ストランド強度５３００ＭＰａ、ストランド弾性率３５７ＧＰａ、配向度８５．４％、結晶子サイズ２．７０ｎｍと、低強度のものであった。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then subjected to surface treatment and sizing, and dried to obtain a carbon fiber. However, the obtained carbon fiber had a low strength of a specific gravity of 1.782, a fiber diameter of 5.0 μm, a strand strength of 5300 MPa, a strand elastic modulus of 357 GPa, an orientation degree of 85.4%, and a crystallite size of 2.70 nm. It was.
比較例１２
表４に示すように、第一炭素化工程における二次延伸処理を、二次延伸が終了するまで比重が上昇し続ける範囲、且つ結晶子サイズが１．４５ｎｍより大きくならない範囲で、延伸倍率１．０３倍で行い、比重１．７０、配向度７９．２％、繊維直径５．８μｍの、糸切れのない二次延伸処理繊維を得、次いで、この処理繊維を第二炭素化処理した以外は実施例１と同様の処理を行った。しかし、得られた第二炭素化処理繊維は、比重１．７９９、繊維直径４．９μｍ、ストランド強度６１００ＭＰａ、ストランド弾性率２８２ＧＰａ、配向度８２．１％、結晶子サイズ１．９１ｎｍと、低強度のものであった。
Comparative Example 12
As shown in Table 4, the secondary stretching treatment in the first carbonization step is performed in a range where the specific gravity continues to rise until the secondary stretching is completed, and in a range where the crystallite size does not become larger than 1.45 nm. 0.03 times, a specific gravity of 1.70, an orientation degree of 79.2%, a fiber diameter of 5.8 μm, and a second stretch-treated fiber without thread breakage was obtained, and then this treated fiber was subjected to the second carbonization treatment The same treatment as in Example 1 was performed. However, the obtained second carbonized fiber has a specific gravity of 1.799, a fiber diameter of 4.9 μm, a strand strength of 6100 MPa, a strand elastic modulus of 282 GPa, an orientation degree of 82.1%, a crystallite size of 1.91 nm, and a low strength. It was a thing.
次いで、この第二炭素化処理繊維を、実施例１と同様に第三炭素化炉において熱処理した後、表面処理、サイジングを施し、乾燥して炭素繊維を得た。しかし、得られた炭素繊維は、比重１．７７２、繊維直径４．７μｍ、ストランド強度５０００ＭＰａ、ストランド弾性率３６２ＧＰａ、配向度８５．８％、結晶子サイズ２．７１ｎｍと、低強度のものであった。 Next, the second carbonized fiber was heat-treated in a third carbonization furnace in the same manner as in Example 1, then subjected to surface treatment and sizing, and dried to obtain a carbon fiber. However, the obtained carbon fiber had a low strength of a specific gravity of 1.772, a fiber diameter of 4.7 μm, a strand strength of 5000 MPa, a strand elastic modulus of 362 GPa, an orientation degree of 85.8%, and a crystallite size of 2.71 nm. It was.
Claims (1)
第一炭素化工程条件
一次延伸条件
(１) ポリアクリロニトリル系耐炎化繊維の弾性率が極小値まで低下した時点から９．８ＧＰａに増加するまでの範囲
(２) ポリアクリロニトリル系耐炎化繊維の比重が１．５に達するまでの範囲
(３) ポリアクリロニトリル系耐炎化繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４５ｎｍに達するまでの範囲
二次延伸条件
(４) 一次延伸処理後の繊維の比重が二次延伸処理中に上昇し続ける範囲
(５) 一次延伸処理後の繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４５ｎｍより大きくならない範囲
第二炭素化工程条件
一次処理条件
(６) 第一炭素化処理繊維の比抵抗値が４００Ω・ｇ／ｍ2以上の範囲
(７) 第一炭素化処理繊維の比重が一次処理中上昇し続ける範囲
(８) 第一炭素化処理繊維の窒素含有量が１０質量％以上の範囲
(９) 第一炭素化処理繊維の広角Ｘ線測定(回折角２６°)における配向度が８０．８％以下で、一次処理中上昇し続ける範囲
(１０) 第一炭素化処理繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４７ｎｍより大きくならない範囲
(１１) 第二炭素化工程一次処理での繊維張力(Ｆ ＭＰａ)と第一炭素化処理繊維の断面積(Ｓ ｍｍ2)とで算出される繊維応力(Ｄ ｍＮ)が下式
１．２４ ＞ Ｄ ＞ ０．４６
〔但し、Ｄ ＝ Ｆ × Ｓ
Ｓ ＝ πＡ2 ／ ４
Ａは第一炭素化処理繊維の直径(ｍｍ)〕
を満たす範囲で繊維張力を与える延伸処理
二次処理条件
(１２) 一次処理繊維の比抵抗値が４００Ω・ｇ／ｍ2未満の範囲
(１３) 一次処理繊維の比重が変化しない又は低下する範囲
(１４) 一次処理繊維の広角Ｘ線測定(回折角２６°)における結晶子サイズが１．４７ｎｍより大きく、且つ二次処理中上昇し続ける又は変化しない範囲
(１５) 第二炭素化工程二次処理での繊維張力(Ｇ ＭＰａ)と第一炭素化処理繊維の断面積(Ｓ ｍｍ2)とで算出される繊維応力(Ｅ ｍＮ)が下式
０．６０ ＞ Ｅ ＞ ０．２３
〔但し、Ｅ ＝ Ｇ × Ｓ
Ｓ ＝ πＡ2 ／ ４
Ａは第一炭素化処理繊維の直径(ｍｍ)〕
を満たす範囲で繊維張力を与える延伸処理 In an inert atmosphere, in the first carbonization step, a polyacrylonitrile-based flameproof fiber having a specific gravity of 1.3 to 1.4 is stretched at a draw ratio of 1.03 to 1.06 within a temperature range of 300 to 900 ° C. A second carbonization treatment obtained by performing a primary stretching treatment, followed by a secondary stretching treatment at a draw ratio of 0.9 to 1.01, and then heat-treating in a temperature range of 800 to 1800 ° C. in the second carbonization step. In the method for producing carbon fiber, in which the fiber is further heat-treated in an inert atmosphere in a temperature range of 1800 to 2500 ° C. in the third carbonization step, the primary stretching treatment in the first carbonization step is performed under the following conditions (1) to ( 3) is performed in a range satisfying both of the above conditions, the secondary stretching treatment is performed in a range satisfying both of the following conditions (4) and (5), and the following conditions (6) to Range that satisfies any of (10) (11) is stretched, and then, as a secondary treatment, (15) is stretched within a range that satisfies any of the following conditions (12) to (14). Further, in the third carbonization step, the above conditions are satisfied. A method for producing carbon fiber to be heat-treated.
First carbonization process condition Primary stretching condition
(1) Range from the time when the elastic modulus of the polyacrylonitrile-based flameproof fiber decreases to a minimum value until it increases to 9.8 GPa
(2) Range until the specific gravity of the polyacrylonitrile-based flameproof fiber reaches 1.5
(3) Range of secondary stretching conditions until the crystallite size reaches 1.45 nm in wide angle X-ray measurement (diffraction angle 26 °) of polyacrylonitrile-based flameproof fiber
(4) Range in which the specific gravity of the fiber after the primary stretching process continues to rise during the secondary stretching process
(5) Range in which the crystallite size is not larger than 1.45 nm in the wide-angle X-ray measurement (diffraction angle 26 °) of the fiber after the primary stretching treatment.
(6) The range of the specific resistance value of the first carbonized fiber is 400Ω · g / m 2 or more.
(7) Range in which the specific gravity of the first carbonized fiber continues to rise during the primary treatment
(8) The range in which the nitrogen content of the first carbonized fiber is 10% by mass or more
(9) The extent of orientation of the first carbonized fiber in the wide-angle X-ray measurement (diffraction angle 26 °) is 80.8% or less and continues to rise during the primary treatment
(10) The range in which the crystallite size of the first carbonized fiber is not larger than 1.47 nm in wide-angle X-ray measurement (diffraction angle 26 °)
(11) The fiber stress (D mN) calculated from the fiber tension (F MPa) in the first treatment in the second carbonization step and the cross-sectional area (S mm 2 ) of the first carbonized fiber is expressed by the following formula 1.24. >D> 0.46
[However, D = F x S
S = πA 2/4
A is the diameter of the first carbonized fiber (mm)]
Secondary treatment conditions for drawing treatment to give fiber tension within the range
(12) The specific resistance value of the primary treated fiber is less than 400Ω · g / m 2
(13) Range in which the specific gravity of the primary treated fiber does not change or decreases
(14) The range in which the crystallite size in the wide-angle X-ray measurement (diffraction angle 26 °) of the primary treated fiber is larger than 1.47 nm and continues to rise or does not change during the secondary treatment
(15) The fiber stress (E mN) calculated from the fiber tension (G MPa) in the second carbonization step secondary treatment and the cross-sectional area (S mm 2 ) of the first carbonized fiber is expressed by the following equation: 60>E> 0.23
[However, E = G × S
S = πA 2/4
A is the diameter of the first carbonized fiber (mm)]
Drawing process that gives fiber tension within the range
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